Medical imaging often includes images of regions of the human body for clinical purposes, such as examination, diagnosis and/or treatment. These images may be acquired by a number of different imaging modalities including for example, ultrasound (US), magnetic resonance (MR), positron emission tomography (PET), computed tomography (CT), mammography (MG), digital radiography (DR), computed radiography (CR) or the like. In a number of example medical imaging workflows, such as in the case of a Picture Archiving and Communication System (PACS), an image study for a patient may include one or more acquired images of the patient along with information that may reside with or otherwise accompany the images.
In order to efficiently and effectively read the medical images, the quality of a medical image should be relatively high. However, the raw image data that is captured, particularly for projection modalities such as DR, CR or MG, may not be of sufficient quality. In this regard, the quality of the raw image data may be dependent upon the quality of the acquisition device, the image capture parameters, the modality type, the technologist's experience, patient variability, the display hardware, the image software and other workflow-related issues. As such, the raw image data may undergo image enhancement processing, such as performed by a quality assurance (QA) workstation. A QA workstation may enhance the image represented by the raw image data by applying one or more different image enhancement techniques.
Image enhancement techniques may be applied with each image enhancement technique designed with a particular objective, such as contrast, noise removal, detail visibility or reconstruction of the original signal. One image enhancement technique utilizes unsharp masking. In unsharp masking, a fraction of the high frequency components of the medical image are added to the original signal. In this regard, a blurred version of the medical image may be subtracted from the medical image itself to create an unsharp mask. Using the mask, the contrast of neighboring pixels may be increased by an amplification amount k. The amplification amount k may be a predefined value that may be, for example, specified by the user to a single value selected from the range of (0 1]. However, unsharp masking enhances both the low and high contrast areas by the same amount of amplification k. For at least some medical images, the enhancement of both the low and high contrast areas by the same amount does not sufficiently enhance the medical image. By way of example, the unsharp masking of an image of a chest X-ray of a patient with pneumothorax, e.g., a collapsing lung, may amplify the lower contrast area proximate the edge of the lung to the same degree as the rib transition to the background such that the edge of the lung remains of lower contrast than would be desired as shown in FIG. 1.
Following the image enhancement of the raw image data, the resulting images may be provided to a PACS for display and review. Depending upon the type of equipment utilized to capture the image and the availability and quality of the QA software that performs the initial image enhancement processing of the raw image data, the PACS may still receive images that are of less than a desired quality and which therefore require additional image enhancement. In an instance in which a user of the PACS, such as a radiologist, is unsatisfied with the quality of the images, the images may again be processed at the QA workstation utilizing different parameters in conjunction with the image enhancement algorithms prior to again being provided to the PACS for further review. Such additional image enhancement processing may create workflow issues and delay the diagnostic process.
Some PACS may also include basic filter processing, such as de-noising and image sharpening. Nonetheless, at least some medical images still have a lower quality than would be desired even after the image enhancement and filter processing. For example, following image enhancement and filter processing, some medical images of certain parts of the anatomy may still have an insufficient contrast and insufficient visibility.